The present invention pertains to the field of microwave communications and more particularly to a multiple layer assembly for connecting microwave integrated circuit modules.
In many applications including communications satellites, Microwave Integrated Circuits (MIC""s) and Monolithic Microwave Integrated Circuits (MMIC""s) are typically packaged in custom-built module assemblies composed of microstrip substrates supported by machined Kovar and aluminum parts. These individual module assemblies are grouped together in a machined aluminum chassis to perform more complex functions. The machined aluminum chassis is a complex array of radio frequency circuit cavities, DC wiring channels and precision mounting bosses, typically custom designed for each application. The resulting assembly is complex, expensive, and capable of achieving only those functions which are designed into it.
One approach is shown, for example, in U.S. Pat. No. 5,363,075, to the assignee of this application. The ""075 patent uses a header supporting a microwave integrated circuit. A domed cover is hermetically sealed to the header. Interconnection pins extend from the bottom of the header and are coupled to a connector assembly. The pins are used for coupling microwave and DC power to the microwave integrated circuit. The RF pins are fed through the assembly for interconnection. A RF ribbon couples the integrated circuit to an RF input. One drawback to such this design is that the labor associated with the assembly is high. This is due in part to the RF feedthrough and the order of operations used in the assembly. One of the most time intensive steps of the assembly process is the tuning of the RF ribbon. For proper operation, the ribbon must be tuned during assembly to obtain the maximum RF coupling. During the tuning process, the shape and length of the ribbon is modified. Also, a number of different tuning techniques may be used. Because of the extreme sensitivity, tuning must be done for each ribbon of the assembly. Numerous ribbons may be used in a satellite.
In communications satellites, there is an ever-increasing need to reduce the size and therefore the weight of the components contained therein. Also, there is a need to increase packaging and connector density, reduce assembly time and number of parts, and improve reliability. Known communication assemblies were relatively large devices and thus had significant weight. Prior art uses coaxial cables or connectors to interconnect slices or units taking up space and weight.
The present invention provides a repeatable, more precise and secure connector assembly, which also is tuneless therefore less labor intensive for interconnecting microwave integrated circuit modules and slices (trays).
In one aspect of the invention, a circuit assembly suitable for RF signals has an integration plate and an RF distribution layer disposed adjacent to the integration plate. The RF distribution layer has an RF conductive layer between a first dielectric layer and a second dielectric layer. A DC distribution layer is disposed adjacent to the RF distribution layer. An RF input is coupled to the RF conductive layer. A module assembly includes an integrated circuit coupled to the RF conductive layer and the DC distribution layer. An RF output is coupled to the RF conductive layer.
In a further aspect of the invention, a method of assembling a circuit comprises the steps of:
mounting an integrated circuit to a header;
coupling a DC pin to the integrated circuit;
positioning an opening in the header sized to receive a contact to directly contact the integrated circuit; and
affixing a cover to the integrated circuit, and thereby forming a circuit module.
One advantage of the invention is that reliability and yield of an assembly formed according to the present invention is increased; cost, cycle time are decreased due to the elimination of parts and processes in the assembly process.
Another advantage of the invention is that numerous high density RF interconnections can be made resulting in smaller modules and units. The interconnection method can be used between slices or units resulting in smaller units and subsystems.